This invention relates to a protective sheath or cap for a bone anchor implantation device. The bone anchor implantation device is used in maintaining or improving urinary continence.
Urinary incontinence, the inability to control urination from the bladder, is a widespread problem in the United States and throughout the world. Urinary incontinence affects people of all ages and can severely impact a patient both physiologically and psychologically.
In approximately 30% of the women suffering from urinary incontinence, incontinence is caused by intrinsic sphincter deficiency (ISD), a condition in which the valves of the urethral sphincter do not properly coapt. In approximately another 30% of incontinent women, incontinence is caused by hypermobility, a condition in which the muscles around the bladder relax, causing the bladder neck and proximal urethra to rotate and descend in response to increases in intraabdominal pressure. Hypermobility may be the result of child delivery or other conditions which weaken, stretch or tear the muscles. In an additional group of women with urinary incontinence, the condition is caused by a combination of ISD and hypermobility.
In males, urinary incontinence may be the consequence of post radical prostatectomy, which can destroy the valves of the urethral sphincter.
In addition to the conditions described above, urinary incontinence has a number of other causes, including birth defects, disease, injury, aging, and urinary tract infection.
Numerous approaches for treating urinary incontinence are available. In one procedure, referred to as bladder neck stabilization (BNS), sutures are placed around the muscles on either side of the urethra and affixed to the rectus fascia or pubic bone and tensioned to treat hypermobility. Other procedures which treat both hypermobility and intrinsic sphincter deficiency (ISD) involve the placement of a sling under the urethra/bladder which compresses the sphincter while simultaneously acting as a stabilizer of the bladderneck (preventing excessive downward mobility). The bone anchors which support the sling sutures may be inserted into rectus fascia or various locations on the pubis bone to provide a non-moveable anchoring method.
The present invention generally relates to devices and methods for inserting anchors, such as bone anchors, into a bone or tissue and more particularly to a protective sheath or cap for isolating the bone anchor to prevent both accidents with the sharp bone anchor before it is inserted into a target site and contamination of the target site by insertion of the bone anchor therethrough.
Bone anchors are often attached into bones in order to provide support for a xe2x80x9cslingxe2x80x9d useful in improving or maintaining a patient""s urinary incontinence. In one procedure, a suture-carrying anchor is driven through the vaginal wall and into the posterior portion of the pubic bone or symphysis pubic, and the suture(s) attached to the bone anchor(s) extend through the vaginal wall and may be attached to the endopelvic fascia, the vaginal wall, a sling, or other material to stabilize and/or slightly compress the urethra thereby improving the patient""s urinary incontinence. The present invention effectively addresses concerns in affixing an anchor to bone or tissue.
The present invention is directed to a protective sheath for the bone anchor. The protective sheath prevents accidents with the sharp bone anchor tip before insertion into the target site, and it prevents infection of the pubic bone. The protective sheath prevents exposure and accidental puncture of the surgeon""s gloves as well as premature insertion into unintended tissue in the patient. It also provides a sterile barrier around the bone anchor. The protective sheath shields the bone anchor from contacting microorganisms in the vagina and area surrounding the implantation site during insertion. The protective sheath of the present invention ensures that the bone anchor implants into the bone implantation site free from contamination and thus prevents the occurrence of biological complications.
One aspect of the present invention is a bone anchor implantation device comprising an elongated member having a first end and a second end, and a related method. A bone anchor is releasably engaged to the elongated member in the vicinity of the first end. A protective sheath is mounted over the bone anchor. The protective sheath can be axially movable relative to the bone anchor such that the bone anchor is exposed from the sheath as the bone anchor is pressed into a bone by the elongated member. Alternatively, the protective sheath can be a balloon, gelatin structure, or other covering that encapsulates or covers the bone anchor prior to implantation. The balloon or thin film can be hermetically sealed around the bone anchor, but in any case the balloon isolates the bone anchor from contact with tissue and prevents contamination prior to implantation of the bone anchor. The balloon is perforated by the bone anchor as the bone anchor is pressed into the bone by the elongated member or shaft. The balloon may be made of a variety of materials such as plastic, thermoplastic, elastromers, PET, PETG, rubber, vinyl, latex, or silicone. In one preferred embodiment, the balloon is made of latex. The balloon can also be made of a biodegradable material. In another preferred embodiment, the balloon comprises a polymer such as a synthetic polymer. Nonlimiting examples of useful polymers include the following: polyglycolic acid (PGA), polyactic acid(PLA), poly (dioxanone) (PDO), poly (l-lactide) (LPLA), poly (dl-lactide) (DLPLA), poly (glycolide-co-trimethylene carbonate) (PGA-TMC), poly (l-lactide-co-glycolide) (PGA-LPLA), poly (dl-lactide-co-glycolide) (PGA-DLPLA), poly (l-lactide-co-dl-lactide) (LPLA-DLPLA), poly(glycolide-co-trimethylene carbonate-co-dioxanone) (PDO-PGA-TMC), poly(xcex5-caprolactone), poly(dioxanone)(a polyether-ester), poly (lactide-co-glycotide), poly(SA-HDA anhydride), poly(orthoester), and polyglyconate. The protective sheath can also take the form of a gelatin structure (similar to a pill capsule).
In some embodiments, the protective sheath (e.g. balloon or gelatin structure) can contain an antibiotic which is released when the sheath is perforated by the bone anchor. The antibiotic prevents infection at the site where the bone anchor is pressed into the bone. Nonlimiting examples of antibiotics which can be used include the following: nafcillin, aminogylcoside, ciprofloxin, clindamcin, piperacillin/tazobactum, ampicillin/sulbactum, aminoglcoside, vancomycin, cephalosporin, TMP/SMN, ampicillin, gentaminicin, tobramycin, and ciprofloxacin. Those skilled in the art will appreciate that there are numerous ways to insert the antibiotic into the balloon or the gelatin structure. In one embodiment, the bone anchor implantation device has a port which extends from the first end to the second end of the shaft into the balloon or gelatin structure. Antibiotics can be inserted into the protective sheath through a port.
In general, in another aspect, the invention features a bone anchor implantation device which has a spring attached to the sheath within the balloon which retracts when the sheath is pressed against the bone by the shaft, thereby causing the bone anchor to perforate the balloon and implant into the bone. The spring element may be an open-coiled helical spring which surrounds the bone anchor. The spring element retracts when pressure is applied to the sheath causing the bone anchor to puncture the balloon.
In some embodiments, the shaft of the bone anchor implantation device can have a hollow section which accommodates one or more sutures coupled to the releasably engaged bone anchor. Also, the shaft preferably is hook shaped.
A method for inserting such a bone anchor that is releasably engaged to such a bone anchor implantation device can include the steps of locating a bone anchor implantation site on the bone and applying a retrograde force to the bone anchor to implant the bone anchor into the bone or to retract the spring to cause the bone anchor to perforate the sheath and implant into the bone.
The foregoing and other objects, aspects, features, and advantages of the invention will become more apparent from the following description and from the claims.